Unused RAM is wasted RAM. Just because an Android phone uses 1.5GB out of 3GB, doesn't mean it's bloated, it's making use of the RAM it has. Just look at OS X, on 10.9 I have 4GB of RAM, and almost all of it is being used after a reboot.
I will give you one example as I have experienced, correct me if I'm wrong.
On Twitter app for iPhone when I click on a link to article it will open up within that app and when I am done reading it it will take me back to the tweets closing that article.
However on android in Twitter app when I click on article it will open that article in my browser (Chrome or default browser). If I hit back button it will take me back to Twitter app but that page will still be open in browser.
After work when I check tweets I and up having more than 10 to 15 tabs in browser, it stays open until I manually close it. Those tabs use RAM which is wasted.
That's one example of optimization I can think of from my daily usage. If android has to run on 1 gb ram it will be disaster not will iPhone.
Just to have same experience as iOS android devices need 2 or 3 GB RAM.